Method for forming resist mask pattern by light exposure having a phase shifter pattern comprising convex forms in the resist

Abstract

A method for forming a resist mask pattern by light exposure providing the steps of forming a resist layer on a semiconductor substrate, forming a phase shifter pattern for inverting a phase of exposed light in an upper portion of the resist layer itself or over the surface of the resist layer, exposing the surface of the semiconductor substrate including the phase shifter pattern, and forming a fine mask pattern below the edge of the phase shifter pattern.

What is claimed is: 
     
       1. A method for forming a resist pattern by light exposure comprising the steps of: i) forming a resist layer having an upper surface on a semiconductor substrate,   ii) forming a phase shifter pattern for inverting the phase of exposure light, said phase shifter pattern comprising convex forms in an upper portion of the resist layer itself,   iii) exposing the whole upper surface of the resulting resist layer including the phase shifter pattern to form unexposed portions positioned below and adjacent to side walls of the convex forms of the phase shifter pattern, and   iv) developing the resist layer, thereby forming a desired resist pattern having a width shorter than a wavelength of the exposure light.   
     
     
       2. The method for forming a resist pattern by light exposure according to claim 1 wherein forming the phase shifter pattern in the upper portion of the resist layer is conducted by light exposure using a mask provided above the resist layer. 
     
     
       3. A method for forming a resist pattern by light exposure comprising the steps of: i) forming a resist layer on a semiconductor substrate,   ii) forming a phase shifter pattern for inverting the phase of exposure light, said phase shifter pattern comprising convex forms, over the resist layer,   iii) exposing the resist layer including the phase shifter pattern to form unexposed portions in the resist layer which are below and adjacent to side walls of the convex forms of the phase shifter pattern,   iv) developing the resultant resist layer to form a desired resist pattern having a width shorter than a wavelength of the exposure light.   
     
     
       4. The method for forming a resist pattern by light exposure according to claim 3, wherein the phase shifter pattern comprises a thin film pattern which is transparent to the exposure light. 
     
     
       5. The method for forming a resist pattern by light exposure according to claim 4, wherein the phase shifter pattern is formed after the thin film layer, which is transparent to the exposure light, is laminated over the surface of the resist layer. 
     
     
       6. The method for forming a resist pattern by light exposure according to claim 4, further comprising forming between the resist layer and the thin film, an intermediate layer which is transparent for the exposure light and is soluble in a developer for the resist layer. 
     
     
       7. The method for forming a resist pattern by light exposure according to claim 4, wherein the resist layer is made of a novolak resin, its surface is treated with a diluted developing solution and a film which is insoluble for the developing solution is then formed on the surface of the resist layer, and the phase shifter pattern is formed on the film which is insoluble for the developing solution. 
     
     
       8. The method for forming a resist pattern by light exposure according to claim 4, wherein the resist layer is made of a novolak resin, its surface is irradiated with ultraviolet rays and a film which is insoluble for the developing solution is then formed on the surface of the resist layer, and the phase shifter pattern is formed on the film which is insoluble for the developing solution.